The first such measuring tool was invented by French inventor Jean Laurent Palmer in 1848.
In 2008, it was patented as "Thread Caliper with Circular Cursor Frame". Today, we still use this typical feature to manufacture outside micrometer.
The introduction of micrometer into the mechanical world began with two American engineers Joseph.
R. Brown and Lucian Sharp visited the Paris Exhibition at 1867, and their attention was caught by Palmer.
Attracted by and very interested in the invention. After improving Palmer's design, the products were manufactured in large quantities and successfully promoted by two partners in the market.
Composition of micrometer:
Its moving part is processed into a screw with a pitch of 0.5mm, and it will move forward or backward by 0.5 mm after rotating in the screw sleeve of the fixed sleeve B, and there are 50 graduations around the screw sleeve. The part larger than 0.5 mm is directly read by the main ruler, and the part smaller than 0.5 mm is measured by the scribing around the movable casing.
Therefore, when measuring the length with a screw micrometer, the reading is also divided into two steps. From the front edge of the movable sleeve to the position of the fixed sleeve, read the number of main feet (pay attention to whether the 0.5 mm short line is exposed). From the number of grids on the movable sleeve opposite to the horizontal line on the fixed sleeve, read out the decimal less than one circle, and the sum of the two is the measured value.
Reference to the above content: Baidu Encyclopedia-Micrometer